MMS ENVIRONMENTAL STUDIES PROGRAM: ONGOING STUDIES
MMS OCS Region: Alaska
Title: Beaufort Sea Nearshore Under-Ice Currents: Science, Analysis, and Logistics (AK-93-48-30, AK-00-X20)
Total Cost: $359,000 Period of Performance: FY 1999-2003
Conducting Organization: University of Alaska at Fairbanks, Coastal Marine Institute (CMI) (FY 1999-2001) and University of Alaska at Fairbanks (FY 2000-2002)
MMS Contact:

Chief, Alaska Environmental Studies Section
Description:
Background
Understanding the under-ice currents is a necessary precursor to estimating potential effects on sensitive resources from oil spills in the landfast ice zone, and in particularly at the Liberty and Northstar projects. The one study of under-ice currents by MMS (in 1978) indicated that under-ice oil spills can move and pose risk to off-site, and in particular, shoreward resources. The 1978 study found that average currents under landfast ice appeared to be related to brine drainage and peak currents to negative surges, with neither related to the regional circulation pattern. The study was unable to measure currents directly under the ice, but instead calculated them from mass-balance considerations to an average of 6 centimeters per second (cm/s) and to peak up to 37 cm/s towards the coast. Depending on the shallowness of the unmeasured pycnocline, these currents may have been faster. Under-ice current speed and direction are important because currents of 10-20 cm/s will move spilled oil along the underside of the ice.
The current ongoing study has provided the first current, temperature, and salinity data covering the entire freeze up, winter, and breakup periods in the nearshore Beaufort Sea. This project provides important information to the MMS Arctic Nearshore Impact Monitoring in Developing Area (ANIMIDA) program.
Objectives
The objectives of this study are to:
  1. Measure currents, temperature, and salinity hourly at three locations in the landfast ice zone in the vicinities of Northstar and Liberty prospects.
  2. Quantify the magnitude of current variability and to describe the relationship between currents and local winds.
  3. Determine the vertical structure of the currents throughout the water column and how the structure changes with the development of the landfast ice through the winter and in summer when the ice melts and rivers flood the inner shelf.
  4. Provide physical oceanographic data to the ANIMIDA study.
Methods
  1. A 1200 kHz acoustic Doppler current profiler (ADCP) has been moored at each of the three sites near Liberty and Northstar prospects for one year. The two moorings closest to Liberty include Sea Cats with transmissometers.
  2. Local winds measured at Deadhorse and sea level data collected at the Waterflood facility will be collated for time-series comparison with mooring data.
  3. Standard physical oceanographic time-series analyses (e.g., univariate statistical descriptors and correlation in both time and frequency domains) and velocity shear calculations will be done.
Importance to MMS
This study will be useful to MMS in evaluating possible cumulative effects from two decades of oil production and industry development along the Beaufort Sea coast. The data from the study will be comparable to the earlier MMS pre-development studies.
Current Status:
The Final CMI report for the 1999-2000 deployment has been completed. MMS has extended the moorings for third year, and added a fourth mooring offshore of the barrier islands.
Final Report Due: CMI Final Report: October 2001

2000-2002 mooring Final Report: May 2003
Publications: Weingartner, T. J. and S. R. Okkonen. 2001. Beaufort Sea Nearshore Under-Ice Currents: Science, Analysis, and Logistics. OCS Study MMS 2001-068, Final Report TO 15169. Fairbanks, AK: University of Alaska Fairbanks, Coastal Marine Institute and USDOI, MMS, Alaska OCS Region. 22 pp.

Weingartner, T. J. 2000. Beaufort Sea Nearshore Under-Ice Currents: Measurements and Analysis [Abstract]. University of Alaska Coastal Marine Institute. Annual Reports No. 6 and 7. Fairbanks, AK, University of Alaska, Coastal Marine Institute and USDOI, MMS, Alaska OCS Region.

Weingartner, T. J. 2001. Beaufort Sea Nearshore Under-Ice Currents: Science Analysis and Logistics. In Alaska OCS Region Eighth Information Transfer Meeting Proceedings, Preparer MBC Applied Environmental Sciences. Anchorage: USDOI, MMS, Alaska OCS Region.
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Revised date: March 2002
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